This invention relates to a tape cassette, and more particularly to a torque-measuring tape cassette.
Still more specifically, the invention relates to a torque-measuring tape cassette for use in cassette recorders and/or players.
Tape cassettes for use in cassette recorders and/or players have two hubs one or the other of which is rotated by a cassette machine capstan, depending upon whether the tape is being advanced or rewound. To achieve proper operation--e.g. to avoid sound distortions due to a tape speed which is either too fast or too slow, or other problems--the torque applied by the capstans in the various tape transport modes (play, record, fast forward, fast rewind) must be within certain predetermined limits. The tape machine manufacturers therefore specify minimum required torque values. When one of these machines undergoes servicing or repair it is, accordingly, necessary to measure the torque output in order to ascertain that the required minimum values are in fact being reached. It is known to use spring-loaded scales for this purpose, but these permit only static measurements to be taken. Moreover, they require the housing to be opened, which is time-consuming and tedious.
A proposal has been made to measure the capstan torque of a tape cassette machine in a simpler manner and during slow tape advancement, by means of a torque-measuring cassette. Such a cassette has a housing and, at the hubs, respective tape-supporting disks or plates each composed of two relatively turnable parts between which a measuring spring is arranged. One of the two parts carries a dial and the other one a pointer; the degree of relative rotation of the two parts is a function of the applied torque, so that this torque can be read off the dial at the value indicated by the pointer.
This is a substantial improvement over the art existing prior to that cassette. However, further improvements are still desirable, for a variety of reasons. For example, during the particularly important measuring of torque in the slow forward modes, the dial turns with the driven tape disk and this makes it more difficult to read the indicated value off the dial. Also, of course, this device can be used only in conjunction with cassette machines in which the tape disk is visible in actual operation; if this part of the cassette is covered in operation of the machine, then the machine must be opened up--or at least the covering part must be dismounted. This is time-consuming. Should the cassette machine be of the type in which only one of the narrow edge faces of the inserted cassette is visible, then any torque-measurement with the known cassette is completely impossible.